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I bought a used Leer cap for my 2010 FX4. I did a search here and found a couple threads that sent me in the right direction but the info wasn't complete. Under the hood on the drivers side between the brake master and fender there are a couple large wiring harnesses. Taped to the outside of one is a black wire and yellow wire and on the other there is a green wire. The green wire is powered only when the brakes are applied and the yellow wire is constant power with the key off or on, if you wire it to a light and leave it on it will trip and turn off as part of the battery protection. These wires are obviously intended by the factory to be used to wire the cap.
Unfortunately you cannot wire into the tail lights to have a steady lit stop lamp on the camper shell. This is because there is not a dedicated stop lamp wire.. if you were to tap into the taillight wiring you would get a blinking 3rd brake light whenever you were making a turn.
Unfortunately you cannot wire into the tail lights to have a steady lit stop lamp on the camper shell. This is because there is not a dedicated stop lamp wire.. if you were to tap into the taillight wiring you would get a blinking 3rd brake light whenever you were making a turn.
Mickey
Ha, I saw one of these going down the road the other day and wondered if the guy knew his LED bar was blinking.
I don't recall exactly where mine is tapped into the tail lights. I do get the blinking cap brake light when either turn signal is on, BUT does turn "solid-on" when my brake pedal is touched. So, changing lanes going down the highway, it blinks. Anytime I touch the brakes--on constant.
That does help, since I bought a used camper shell this weekend. But help me out with the colors, which ones do what?
Rereading the original post, I do see where the green wire is the brake line, and the other is for lights in the camper.
But the reason I'm asking is, it comes with a pigtail connector that has three wires. I'm trying to figure out what that third is! Maybe one ground, one power, and one to the overhead light? I'm guessing, but it does sound logical.
Dumb question of the day: I assume the third black wire is a ground. Is there any advantage of using that wire to ground the cap versus just picking up a frame ground somewhere near the cap?
Also, my yellow wire has a green stripe. In your first picture, that appears to be the case as well. The dome light and brake light are both working properly. I went ahead and hooked the ground up to the frame.
Last edited by thrifty biil; 04-04-2016 at 07:47 PM.
I wanted to provide this info in one place for anyone putting on a truck cap / camper shell themselves. I spent hours looking for these wires and want to make it easier for the next person. The dedicated wires are under the hood on the driver's side close to the firewall / over the Left front fender.
Blue with orange stripe on driver's side firewall under the hood = dedicated truck cap brake light
Yellow with green stripe on driver's side firewall = dedicated truck cap dome light
I connected to these two wires and ran them to the back of the truck following the existing harness all the way back to the Driver's side tail light. I pulled the two screws holding the taillight and pulled the taillight out slightly to get to the wires/holes. ran the 2 wires from the front, up through the holes and made all connections inside the taillight area. I used a standard 4 wire trailer harness to wire the top. There are 4 wires coming from the top (2 brake / 2 dome) I wired both black ground wires together and splice clamped them into the driver's side brake light (black ground wire.) Then I wired the two wires from the front into the connector. (I did not use one of the four wires in the connector because I put the two black grounds together from the truck cap.) I am happy with my install considering I saved a lot of money. An outfitter in the St. Louis area wanted $80 to wire it and would not tell me where the wires were.
**** If you install it the way I did the dome light will time out and shut off after 10 min to save your battery. To get it back on, just hit the lock/unlock button on your key or open the door. I love it this way. I hope this helps someone in the future and saves them research time.
FireDawg_20
2014 XLT Crewcab Ecoboost
Last edited by firedawg_20; 06-21-2016 at 11:42 AM.
Just a "for what it's worth"... Shouldn't these feeds be stubbed off somewhere in the rear of the truck--say, behind a tail-light--instead of under the front hood?? The cap does go on the rear of the truck after all. I guess Ford would rather have owners pay for all that wiring vs having it already wired to the rear where it should be... Just sayin'
03-19-2014, 11:16 PM
Wiring a cap topper brake and dome
